Opaque materials have been used for creating imagery throughout history. When applied to wall settings, we have seen high-relief surfaces (e.g., bas relief), that are sculpted close to the subject's three-dimensional reality, giving bright highlights and casting shadow through their three-dimensional shape. Shallow relief on walls gives similar light and shade, but achieves it with less relief. Bas relief achieves a light/dark effect through the same realistic rendering of the image as shallow relief but does it at a level below the normal surface of the wall rather than protruding from it. All these types rely on a changing height of the image based on or simulating the shape being depicted.
Grooves and ridges have been used as a method of articulating surfaces in walls and flooring. Grooves and ridges have been used to articulate various parts of buildings, normally in straight lines and/or parallel/equidistant lines, and normally to highlight architectural features. They have been used as component parts of statuary and other representational artwork, and in the case of abstracted art forms, particularly in the Art Deco period, to form abstract decorative motifs. Such grooves or ridges normally have a flat frontal surface which causes the shadow portions generated to be a minor component of the design, and this type of ridge is unsuitable for producing anything but the simplest motifs. Current practice is to place vertical ridges, with flat frontal surfaces between them, on exterior walls as a means of decoration. In cases where ridges are used without the flat frontal surface, it is to produce chevrons and similar decorative motifs. When used with flooring, ridges may be seen to be arranged uni-directionally, or in squares and these may be arranged with the ridges alternating between “vertical” and “horizontal” in a checkerboard effect. Other materials, such as plaster, may have random shallow grooving as a way to mask unevenness in troweling on the material. In these usages, the purpose is for a general overall uniform effect, as opposed to producing a dynamic image produced by differences in light and shade.
Grooves or ridges have long been used in sculpture to reproduce the shapes found in nature, as in the depiction of clothing or drapery. Grooves and ridges are also found in decorative panels as portions of the panel that differ in texture from surrounding areas, such as in the egg and dart pattern and others found in architectural decoration. In these decorative uses, the grooves or ridges are part of the composition, and do not serve to produce a complete image by differences in light and shade.